Water-setting cement composition



Patented Aug. 10, 1948 UNITED STATES rtrf' PATENT OFFICE 2,44a99owarm-ss'r'rmc CEMENT COMPOSITION Clyde 0. Schuetz, Mount to UnitedStates Gypsum Prospect, Ill., assignor Company, Chicago,

111., a corporation of Illinois No Drawing. Application November 29,1943,

Serial No.

Claims. 1

The present invention relates to a water-setting F cement compositioncomprising substantial quantities each of finely ground water-granulatedb last furnace slag, fly ash, and Portland cement;

particularly when said composition isemployed 5 to form sheet productscontaining substantial quantities of inorganic fibers, as for example,as:

, bestos fibers.

The i'rivention relates moreover to a process for the production ofmolded materials comprising the set reaction products of finely groundwatergranulated blast furnace slag, Portland cement, and fly ash, eitherwith or without admixture with an inorganic fibrous material such asasbestos fibers. The invention also comprises activatin groundwater-granulated b ast furnace slag as a cementing a eITtby the reactionthereth of fly ash and a minor propor ion'b? Po tland cement in thepresence of water.

The manufacture of cementitious material from slag has been practicedfor many years, but in general cements made from blast furnace slag havenot found a great deal of favor particularly as they do not keep verywell. For instance, it has been suggested to mix blast furnace slag withd ne, and also small quantftiesbfsodiumhydrom ide or sodium sulfate, soas to ootaina mnuue FaTving' hy'draiilicproperties. Such mixtures,however," havehotbeen particularly popular, primarily because of thegeneral failure on the part of the manufacturers thereof to understandthe necessity that the slag employed must be of the water quenchedvariety, and that no really useful product can be obtained from themerely air; cooled so-called bank sla g; and moreover'that even cementsmade from proper slag deteriorate rather rapidly in storage as comparedwith Portland cement, which latter has good keeping qualities.

As is well known, formed products and molded products, particularly inthe form of sheets such as are used for partitions, sidings andshingles, have long been made from a mixture of sbestgs fibers andcement, generally known as ber cei'nent or asbestos cement, having beenworked up ll bytwo well known methods, one of these being the so-calledwet or "Hatschek process, and the other a ary'preesfomn named after itsinventor, the "Norton process. The wet, gal-, schek process comprises"making a mixture'of as; 5 f l ies,tos,- say from 15% to 20% with from85%"?6 80% of Portlandpement, beating this mixture, as for instance in apaper beater, until the cement and the fibers have absorbed considerablewater, and then building up a laminated sheet from the .86 mixturebypicking it up on felts, transferringit to an accumulator roll, andeventually cutting the laminated cylinder thus obtained, flattening itout, pressing it, and permitting the cement to set. This so-calledHatschek process has been very 60 widely applied in all parts of theworld for the method of 15 2 making of sidings, shingles and otherbuilding elements.

In the Norton process there is prepared a dry mixture insubstantiallythe same proportions as in the Hatschek process. This dry mixture is Ispread out into a sheet having about two or three times the thickness ofthe article which is to be made, whereafter the mixture is compacted dryby means of rollers, and is then sprayed with enough water to wet it sothoroughly that the setting of ti? cementitious ingredient can takeplace. Sometimes there is also additional compression after the wettingoperation, but in any event, the setting ingredient in all of theseasbestos cement products has been Portland cement.

The constantly growing demand for products of this type, and theincreasing competition between the different products on the market, hasled to a search for a more economical binding material than theconventionally used Portland cement. Of course, it was not desired tosacrifice either strength or durability in the product. The substitutionof other cementitious materials has been beset by all kinds ofdifficulties, but particularly by the fact that many of the bondingmaterials proposed do not permit of filtration of the material withsufficient rapidity to permit the manufacture of the product on the wetmachine by the Hatschek process, or if they can be made that way,require such a slowing .up of the felt speed as to render the processuneconomical.

Furthermore, the bonding ageng in order to lend itself to the operationsof the Hatschek process,

must be free gi strongly alkaline chemicals by reason of'the' fact thatthe woblilts used in the process are readily destroyed by the solventaction of alkalies. In accordance with the present invention it has beenfound that the Portland ggment in such .as- V" bestoscement mixturejgnbe replace almost entirel B a setting material cosssui?orann fur T% e oneiz ound water-granulated blast furnace s a an e ma erial own as Thelatter is the fine ash or flue dust carriea'b'y the combustion productsof pulverized coal plants. 5 Thus, where pulverized coal is used as afuel, the rush of gases and the force of propulsion of the finelydivided oal particles causes the coal to burn with along white flame,and by reason of the speed of the combustion gases these will carryforward with them into the fines, stacks, and seti'lin chambers, -theincombustible ingredients of the coal, which settles out in these duesand chambers in a very finely powdered form, being known to the art asfly ash. It appears that by ;reason.of its extremely fine subdivision,the fly ainamql f decomlo sin I glwsduswh the resence of water and willin some manner; reicfi IHEEE in;

Mandamus: we: Portland cement, to yield a mixtuge -:.?which is capableof setting hydraulically.

DlAlilNER The effect of the gy sh and a minor proportion of ortla ndcement therefore isin some respects similar to the eifect of lime andsodium hydlg fia difthe greunasiag, except that the 'mixture will neverreact strongly alkaline, as it would if sodium hydroxide were used.Inasmuch as lime, in admixture with ground blast slag, forms a very slowfiltering mixture, such a bonding agent is not suitable for themanufacture, for example, of asbestos cement sheets even in the absenceof sodium hydroxide. However, by employing a mixture of groundwater-granulated blast furnace slag and fly ash, together with a maamoun or and cement, it was found that asbestos cement prmucfi comd be.made by the wet process on the regular machines with substantially nochanges in the operational details of the process.

Attempts have been made to useblast furnace slag as a cement, withsodium hydroxide as a catalvzer, but inasmuch as in the wet or Hatschekprocess a closed system is used through which all the excess watercirculates, it is self-evident that there'will be a build up of solublealkali which is intolerable because of its effect on the felts, andhence requires that the system must be frequently drained for cleaning.Moreover, if too great a quantity of soluble salts is left in theproduct,-as would be the case if sodium sill; i f a i3a were used as acatalyzer, this will eventually emoresce and form a most undesirablebloom on the material.

Based upon the above consideration, and in accordance with the presentinvention, the cementitious -or setting portions of the mixture(calculated on the fiber-free basis) may consist substantially of thefollowing: Portland cement, not substantially -below15%, and nor steamtially more than 85% of .a mixture of g atergranulated biast furnaceslag,'and ily ash, which re 'ash, however, should not be substantiallyless thanq s of the quantity of the slag employed, "nor more than about/5 of the cementitious mixture. The amount of Portland cement in themixture can of course heme-reams, and products may be made which howeverare those of the prior art) in-wiiich the Portland cement would replaceall ofithe slag and fly ash. However, there is little advantage tobegained from the use of less than about of A slag in the mixture. Inother words, the mixture of fly ash and slag is a suh:

stitute.for a portionmi the Portland cement which has previously been"used for making asbestoscement products, and this substitution is theuintessence of the present invention.

In general, the limitations or range of ingredients so far as thecementitious or setting ingredient is concerned, may be as follows:

Within .the range above shown, there maybe made up a mixture for themanufacture of asbestos cement products having about the foliowingformula:

'Percent Asbestos fiber -'15 Water granulated :blast fumace slag 64Portland cement '18 Fly ash 8 Dried and ground to a flnenms ;of .8793through e825 mesh sieve.

4 A mixture such as the above may be suspended in sufllclent Et to forma slurry which is then placed in the pick-up tanks of the Hatschek ma--.:chine from which a plurality of layers are picked 5 up, there being asuccession of such pick-up tanks containing the pick-up cylinders, overwhich the .falt successively passes, thus picking up succes- Wethin-layers of .the wet mixture, thus building np-alaminated sheet whichis eventually col- 10 lected on a collecting roller, from which it is;;stripped, flattened out, and then pressed, and permitted to set. It isnot believed necessary in this-specification to recite all of thedetails of the making of the cement sheets, as these have been so fullydescribed in the Hatschek patents and improvements thereon as to befamiliar to everyone in this art.

rAlternatively, the mixture thus described may be fm'medmnto a compactedmass, in accordonce with the ,Iiorton process, and then sufiicientlywetted to cause the material to set.

It is of course obvious that the invention is not circumscribedby thedetails given above, but that thezmixture of fly ash, finely groundwater-granug5 lated blast furnace slag, and Portland cement,

may be used in admixture with suitable a ggtes be they fibrous orotherwise, for the formation of themolded cementitious articles.

-lMoreover the exact formula given is purely 80 exmnplificative, and anyproportion of mixtures within the broad ranges hereinabove stated is tobe considered within the scope of the hereunto appended claims, in whichthe invention as laimed comprises:

85 1. A water-setting cementitious mixture consisting of 15% of asbestosfiber, 64% of watergranulated ast f ace la dried and ground toa'iineness of 87%througir'532'5 mesh sieve, 18% of Portland cement, and8% of fly ash.

40 A fiber cemen a es 1 rom the setting of the. composition as claimedin claim 1.

3...A--water.setting cement composition comprising from zabout 15% to89% of Portland cement;:t'rom-about 1 o to a of water-granu- Wgmund to afineness such at least about 87 0 thereof will pass througha325rmrhhscreen, and from about 1% to 20% ofifly-ash.

i ecement article comprising a fibrous aggregate bonded by a set cementcomposition as'niaimed in-.claim.3.

65A fiber-cement article as claimed in claim 4, in which the fibrousaggregate is asbestos.

CLYDE C. SCHUETZ.

7 REFERENCES CITED 'The-following'referencesare of record in theflle'ofthis patent:

